1. Field of the Invention
This invention relates to jet powered watercraft, especially personal watercraft (xe2x80x9cPWCxe2x80x9d). More specifically, the invention concerns control systems that assist in maneuvering jet powered watercraft when the jet pump fails to produce sufficient thrust to assist in directional control of the watercraft. In particular, the invention is directed to steering assistance for a PWC.
2. Description of Related Art
Jet powered watercraft have become very popular in recent years for recreational use and for use as transportation in coastal communities. The jet power offers high performance, which improves acceleration, handling, and shallow water operation. Accordingly, PWCs, which typically employ jet propulsion, have become common place, especially in resort areas.
As use of PWCs has increased, the desire for better performance and enhanced maneuverability has become strong. Operators need to be able to handle the watercraft in heavily populated areas, especially to avoid obstacles, other watercraft and swimmers. Also, as more people use PWCs as a mode of transportation, it is also preferred that the craft be easily docked and maneuvered in public places.
Typically, jet powered watercraft have a jet pump mounted within the hull that takes in water and expels the water at a high thrust to propel the watercraft. Most PWCs operate with this system. To control the direction of the watercraft, a nozzle is generally provided at the outlet of the jet pump to direct the thrust, or flow of pressurized water, in a desired direction. Turning is achieved by redirecting the thrust. In conventional, commercially available PWCs, the only mechanism provided for turning is the nozzle.
The nozzle is mounted on the rear of the craft and pivots such that the thrust may be selectively directed toward the port and starboard sides within a predetermined range of motion. The direction of the nozzle is controlled from the helm of the watercraft by the person operating the craft. By this, the operator can steer the watercraft in a desired direction. For example, when a PWC operator chooses to make a starboard-side turn, he or she turns the helm clockwise. This causes the nozzle to be directed to the starboard side of the PWC so that the thrust will effect a starboard turn.
During operation, when the user stops applying the throttle, the motor speed (measured in revolutions per minute or RPMs) drops, thus slowing or stopping the flow of water through the nozzle at the rear of the watercraft. This results in reducing the thrust generated by the pump. Accordingly, the water pressure in the nozzle drops. This is known as an xe2x80x9coff-throttlexe2x80x9d situation. This can occur at low vehicle speeds, for example when the operator is approaching shore or a dock, or at high vehicle speeds, when the operator releases the throttle.
Thrust will also be reduced if the user stops the engine by pulling the safety lanyard or pressing the engine kill switch. The same condition occurs in cases of engine failure (i.e., no fuel, ignition problems, etc.) and jet pump failure (i.e., rotor or intake jam, cavitation, etc.). These are known as xe2x80x9coff-powerxe2x80x9d situations. For simplicity, throughout this application, the term xe2x80x9coff-powerxe2x80x9d will also include xe2x80x9coff-throttlexe2x80x9d situations, since both situations have the same effect of reducing pump pressure and thus reducing thrust.
Since the flow of pressurized water is the thrust that causes the vehicle to turn, when the thrust is reduced or eliminated, steering becomes less effective. As a result, a need has developed to improve the steerability of PWCs under circumstances of insufficient thrust when the pressure generated by the pump has decreased below a predetermined threshold. This is particularly significant when docking or when driving through low wake areas. This is also important when the vehicle is operating at high speeds and the throttle is released, which would create a situation where steering assistance is needed.
One example of a prior art system is shown in U.S. Pat. No. 3,159,134 to Winnen, which provides a system where steering assistance is provided by vertical flaps positioned at the rear of the watercraft on either side of the hull. In this system, when travelling at low speeds, the thrust from the propulsion system provides minimal steering for the watercraft. When the operator turns the helm, one of the side flaps pivots outwardly from the hull into the flow of water with a flap bar to improve steering control. However, this system is not advantageous for several reasons discussed below.
A system similar to Winnen is schematically represented by FIG. 18, which shows a watercraft 1100 having a helm 114. Flaps 1116a, 1116b are attached to the sides of the hull via a flap bar 1128a, 1128b at a front edge. Two telescoping linking elements 1150a, 1150b are attached to arms 1151a and 1151b, respectively, at one end and to the respective flap bars 1128a, 1128b at the other end, respectively. Arms 1151a, 1151b are attached to partially toothed gears 1152a, 1152b, respectively. A central gear 1160 is positioned between the gears 1152a and 1152b to engage them, and is operated, through a linking element 1165 and a steering vane 1170, by the helm 1114. FIG. 18 illustrates the operation of the flaps when the watercraft is turning to the right, or starboard, direction.
Because the gears 1152a, 1152b are only partially toothed, when attempting a starboard turn, only the right gear 1152b will be engaged by the central gear 1160. Therefore, the left flap 1116a does not move but, rather, stays in a parallel position to the outer surface of the hull of the PWC 1100. Thus, in this configuration, the right flap 1116b is the only flap in an operating position to assist in the steering of the watercraft 1100.
While the steering system of FIG. 18 provides some level of improved steering control, the system suffers from certain deficiencies. First, steering is physically difficult. When the flap bars 1128 are located at the front portion of the flaps 1116 (as shown), the user must expend considerable effort to force the flaps 1116a, 1116b out into the flow of water. Second, the force needed to force the flaps 1116a, 1116b into the water stream causes considerable stress to be applied to the internal steering cabling system that may cause the cabling system to weaken to the point of failure. Third, only one flap 1116b is used at any given moment to assist in low speed steering. Therefore, steering assistance is provided on one side of the watercraft only. Fourth, when the helm is turned, the one usable flap is always operative. Thus, when the helm is turned while the watercraft is operating at a high speed, with sufficient thrust, the flap is pivoted into the high pressure flow of water past the hull. This can cause damage to the flap and its associated components and can make handling more aggressive.
Thus, the steering system shown in FIG. 18 is difficult to use, applies unacceptable stresses to the internal steering system, relies on only half of the steering flaps to effectuate a turn, and cannot be disengaged when steering assistance is not desired.
For at least these reasons, a need has developed for an off-power steering system that is more effective in steering a jet powered watercraft, especially a PWC, when the thrust is inadequate because the pump pressure has fallen below a predetermined threshold. Preferably, the steering system should provide accurate handling with easy operation.
Therefore, one aspect of embodiments of this invention provides an off-power steering system that does not cause undue stress on the driver or the helm control steering mechanisms.
An additional aspect of the present invention provides an off-power steering mechanism that does not interfere with operation of the watercraft when sufficient thrust is generated by the jet pump to steer the watercraft.
A further aspect of the present invention provides a high degree of maneuverability by providing supplemental steering assistance on both sides of the watercraft.
In summary, this invention is directed to an off power steering system for a personal watercraft comprising a hull, a deck mounted on the hull, and a jet propulsion system positioned in a tunnel of the hull and connected to a steering nozzle at the stem of the hull. The deck supports a straddle seat and a helm with steering handles. A movable vane is mounted on both sides of the hull and spaced a predetermined distance from the side wall of the hull. An actuator operatively connects the vanes and the helm so that the vanes are operable from the helm. The vanes act as mechanisms to deflect the flow of water adjacent to the hull, which causes the watercraft to change direction.
More particularly, this invention relates to a watercraft comprising a hull with an operator""s area, a jet propulsion system supported by the hull, and a helm with a steering controller located in the operator""s area. To assist with steering, a pair of vanes are supported on opposed sides of the hull for movement with respect to the hull. A first actuator is coupled between the steering controller and each of the vanes to transmit steering signals to at least one of the vanes to pivot the vane with respect to the hull. A second actuator is coupled between the jet propulsion system and each of the vanes to move the vane between a lowered, operative position and a raised, inoperative position.
Preferably, the watercraft is a personal watercraft (PWC). The PWC can be a straddle type seated PWC or a stand-up PWC. Additionally, the watercraft could be different types of jet powered watercraft, such as a jet boat, or even a watercraft powered by a conventional propeller driven system.
The watercraft can be powered by a jet propulsion system that includes a nozzle positioned at the outlet of the propulsion system that is operatively connected to the steering controller, so that the nozzle pivots in response to steering signals and directs the pressurized stream of water in a desired direction to effect turning. A first actuator in the form of a connector can be provided through the hull between the nozzle and the vanes to transmit steering signals from the nozzle to the vanes. The connector can have shock absorbing mechanisms to prevent or reduce the transmission of forces experienced by the vanes to the nozzle. Further, rather than using a nozzle, the steering of the watercraft could be effected by a rudder disposed at the outlet of the jet propulsion system.
The vanes are preferably pivotally connected adjacent to the stern of the watercraft, with one vane on each starboard and port side. Upon receiving a steering command, the vanes can pivot into the flow of water to deflect water and assist with steering. The vanes can be spaced from the hull wall to allow water to flow on both sides of the vane when in certain positions. The vanes can also be provided with through holes to allow water to pass through the vanes and grooves with fins to allow water to flow over the vanes to facilitate flow over the vanes and reduce stress to the vane structure.
The vanes can be moved from an operative position at or below the waterline to an inoperative position above the waterline, when the vanes are not needed, as determined based on the sufficiency of thrust provided by the jet propulsion system. When thrust is reduced or insufficient as evidenced by low pressure in the jet propulsion system, the vanes can be lowered, automatically or selectively, into an operative position.
Such movement can be effected by a second actuator in the form of a hydraulic system that raises or lowers the vanes in response to pressure generated in the pump. While the pressure can be transmitted by signals, it is preferred that the system includes a direct connection to the jet propulsion system. A hydraulic cylinder and piston rod associated with the mounting system of the vane can control the movement of the vane by moving the vane up by a pressure command or down by a spring biased response. A blocking device can be provided to limit downward movement of the vane. In that case, the vane will only move into the operative position when a steering command is received.
In summary, this invention is directed to a personal watercraft comprising a hull having a pair of side walls and bottom with a tunnel, a helm supported by the hull and having a steering member, and a jet propulsion unit supported by the hull in the tunnel and having an inlet that draws in water and an outlet that expels a pressurized stream of water as thrust that propels the personal watercraft. A nozzle is attached to the outlet and directs the pressurized stream of water in response to the steering member to steer the personal watercraft in a desired direction. A side vane is supported by each side wall of the hull. Each vane is operatively connected to the steering member to pivot with respect to the associated side wall in response to movement of the steering member and is operatively connected to the jet propulsion unit to raise and lower with respect to the side wall in response to pressure in the jet propulsion unit.
These and other aspects of this invention will become apparent upon reading the following disclosure in accordance with the Figures.